联合收割机双闭环负荷控制系统的设计

联合收割机是一个高阶时变非线性系统,存在大滞后,工况复杂,简要分析联合收割机数学模型及作业期间可能存在的各种内部、外部扰动。针对收割机负荷控制系统中利用一个控制器综合多个扰动,各参数相互影响,参数调整困难,系统动态性能不够好的问题,提出一种双闭环负荷控制系统,将收割机系统分为行走、作业两部分,分别利用车速闭环和滚筒转速闭环进行控制。车速闭环采用单神经元比例积分微分(Proportion,integration,differentiation,PID)算法,根据车辆行走系统的工况变化不断调整控制参数,尽可能跟踪给定车速。滚筒转速闭环采用直接广义预测控制算法,也可自动适应系统参数和工况的变化,保证滚筒恒定在最佳转速。整个控制算法实时计算量较小,可保证系统具有足够高的实时性。仿真和试验证明双闭环负荷控制系统能获得较高的控制精度和优良的动态特性。

Design of Combine Load Control System Based on Double Loop

Combine is a higher-order system with time-varying characteristics,nonlinear characteristics,and large delay time.Its working condition is complex.The mathematical model of combine and the internal,external disturbance are analyzed briefly in this paper.There are many problems in load control system using one controller,such as too many disturbances affecting the controller,mutual influence between parameters,difficulties in adjusting the parameters,and the dynamic performance is not good enough.A double loop control system was studied.Combine is divided into walking part and operating part.The walking part is controlled by vehicle speed controller and the operating part is controlled by threshing cylinder controller.The vehicle speed controller use single neuron PID.Controller adjust the system parameters according to the changes of the walking condition to keep the vehicle speed is equal to the desired value.The threshing cylinder controller use direct generalized predictive control.The controller can automatically adapt to the changes of the system parameter and working conditions and keep the cylinder’s rotate speed constant at the optimum speed.The algorithm in the controllers has smaller computation load,and can meet the real-time requirements.The simulation and test show that the system can access to higher control accuracy and better dynamic characteristics.